OCLC's WorldCat database contains 849 million holdings listings for the purpose of associating WorldCat's 48 million bibliographic records with the 41,000 participating libraries in 82 countries that possess those items. In 2001, OCLC celebrated the 30th anniversary of WorldCat. If libraries haven't been diligent about removing holdings of weeded and lost materials, 30 years is a long time for obsolete holdings to accumulate. As OCLC develops new plans to extend the resource sharing capabilities of WorldCat, the reliability of these holdings becomes increasingly important. To the extent that problems exist, these findings can be used to encourage libraries to be more diligent in removing obsolete holdings or perhaps to justify efforts to develop solutions to keep them current. Because this was a pilot study, the sample was limited to books held by members of the OhioLINK consortium. This allowed the author to compare OCLC's holdings against the consolidated catalog for the consortium. While OhioLINK institutions may not perfectly reflect OCLC's current library membership, most of them can claim a long history with OCLC dating back to its origin as the Ohio College Library Center in 1967. This study finds that overall, 7.69% of OCLC's holdings are obsolete compared to the OhioLINK catalog. Little difference was found between ARL and non-ARL institutions. Non-fiction materials made up the bulk of materials sampled and the error rate of 7% for them was in line with the overall rate. The few fiction items in the sample, however, did show an elevated error rate of 20%. Likewise, sampled materials published prior to 1900 were small in number, but exhibited a high error rate of 27%.